The popular Whatsapp? messaging tool might be the next big money mobile acquisition, with Facebook said to be aiming its enormous wallet in the direction of the cross-platform chat app.

Whatsapp? is believed to have more than 100 million active users who transfer around 1 billion messages a day, all using data and wi-fi connections that operate outside of the traditional mobile network calling and texting allowance.

What's particularly interesting it that a deal would see Facebook buying an app that's currently paid for by its users, with the maker of Whatsapp? currently asking for 69p in return for the iOS version, while the Android app is free for two months then 69p a year after that.

Considering it's ad-free that's seen as quite a good deal, and the nigh-on two million user reviews of the Android app confirm its rampant popularity. [TechCrunch]